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Welcome to the new Freedom to Tinker

September 17, 2008 by

Welcome to the new, redesigned Freedom to Tinker. Beyond giving it a new look, we have rebuilt the site as a blogging community, to highlight the contributions of more authors. The front page and main RSS feed will offer a combination of posts from all authors. We have also added a blog page (and feed) for each author, so you can read posts by your favorite author or subscribe to your favorite author’s RSS feed. Over time, Freedom to Tinker has evolved from a single-author blog into a group effort, and these changes better recognize the efforts of all of our authors.

Along with the redesign, we’re thrilled to add three authors to our roster: Tim Lee, Paul Ohm, and Yoshi Kohno.

Tim Lee is a prominent tech policy analyst, journalist, and blogger who has written for sites such as Ars Technica, Techdirt, and the Technology Liberation Front. He is now a computer science grad student at Princeton, and a member of the Center for Information Technology Policy.

Paul Ohm is an Associate Professor of Law at the University of Colorado, specializing in computer crime law,criminal procedure, intellectual property, and information privacy. He worked previously as a trial attorney in the Computer Crime and Intellectual Property Section of the U.S. Department of Justice; and before law school he worked as a computer programmer and network administrator.

Yoshi Kohno is an assistant professor of computer science and engineering at the University of Washington. His research focuses on assessing and improving the security and privacy properties of current and future technologies. In 2007 he was recognized by MIT’s Technology Review magazine as one of the world’s top innovators under the age of 35. He is known for his research on the security of implantable medical devices and voting machines, among other technologies.

Finally, Freedom to Tinker is now officially hosted by Princeton’s Center for Information Technology Policy. A major goal of CITP is to foster discussion of infotech policy issues, so it makes sense for CITP to host this kind of blog community for CITP members and friends.

We hope you enjoy the new Freedom to Tinker. As always, we welcome your comments and suggestions.

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It can be rational to sell your private information cheaply, even if you value privacy

September 5, 2008 by

One of the standard claims about privacy is that people say they value their privacy but behave as if they don’t value it. The standard example involves people trading away private information for something of relatively little value. This argument is often put forth to rebut the notion that privacy is an important policy value. Alternatively, it is posed as a “what could they be thinking” puzzle.

I used to be impressed by this argument, but lately I have come to doubt its power. Let me explain why.

Suppose you offer to buy a piece of information about me, such as my location at this moment. I’ll accept the offer if the payment you offer me is more than the harm I would experience due to disclosing the information. What matters here is the marginal harm, defined as amount of privacy-goodness I would have if I withheld the information, minus the amount I would have if I disclosed it.

The key word here is marginal. If I assume that my life would be utterly private, unless I gave this one piece of information to you, then I might require a high price from you. But if I assume that I have very little privacy to start with, then selling this one piece of information to you makes little difference, and I might as well sell it cheaply. Indeed, the more I assume that my privacy is lost no matter what I do, the lower a price I’ll demand from you. In the limit, where I expect you can get the information for free elsewhere even if I withhold if from you, I’ll be willing to sell you the information for a penny.

Viewed this way, the price I charge you tells you at least as much about how well I think my privacy is protected, as it does about how badly I want to keep my location private. So the answer to “what could they be thinking” is “they could be thinking they have no privacy in the first place”.

And in case you’re wondering: At this moment, I’m sitting in my office at Princeton.

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Cheap CAPTCHA Solving Changes the Security Game

September 2, 2008 by

ZDNet’s “Zero Day” blog has an interesting post on the gray-market economy in solving CAPTCHAs.

CAPTCHAs are those online tests that ask you to type in a sequence of characters from a hard-to-read image. By doing this, you prove that you’re a real person and not an automated bot – the assumption being that bots cannot decipher the CAPTCHA images reliably. The goal of CAPTCHAs is to raise the price of access to a resource, by requiring a small quantum of human attention, in the hope that legitimate human users will be willing to expend a little attention but spammers, password guessers, and other unwanted users will not.

It’s no surprise, then, that a gray market in CAPTCHA-solving has developed, and that that market uses technology to deliver CAPTCHAs efficiently to low-wage workers who solve many CAPTCHAs per hour. It’s no surprise, either, that there is vigorous competition between CAPTCHA-solving firms in India and elsewhere. The going rate, for high-volume buyers, seems to be about $0.002 per CAPTCHA solved.

I would happily pay that rate to have somebody else solve the CAPTCHAs I encounter. I see two or three CAPTCHAs a week, so this would cost me about twenty-five cents a year. I assume most of you, and most people in the developed world, would happily pay that much to never see CAPTCHAs. There’s an obvious business opportunity here, to provide a browser plugin that recognizes CAPTCHAs and outsources them to low-wage solvers – if some entrepreneur can overcome transaction costs and any legal issues.

Of course, the fact that CAPTCHAs can be solved for a small fee, and even that most users are willing to pay that fee, does not make CAPTCHAs useless. They still do raise the cost of spamming and other undesired behavior. The key question is whether imposing a $0.002 fee on certain kinds of accesses deters enough bad behavior. That’s an empirical question that is answerable in principle. We might not have the data to answer it in practice, at least not yet.

Another interesting question is whether it’s good public policy to try to stop CAPTCHA-solving services. It’s not clear whether governments can actually hinder CAPTCHA-solving services enough to raise the price (or risk) of using them. But even assuming that governments can raise the price of CAPTCHA-solving, the price increase will deter some bad behavior but will also prevent some beneficial transactions such as outsourcing by legitimate customers. Whether the bad behavior deterred outweighs the good behavior deterred is another empirical question we probably can’t answer yet.

On the first question – the impact of cheap CAPTCHA-solving – we’re starting a real-world experiment, like it or not.

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Gymnastics Scores and Grade Inflation

August 21, 2008 by

The gymnastics scoring in this year’s Olympics has generated some controversy, as usual. Some of the controversy feel manufactured: NBC tried to create a hubbub over Nastia Liukin losing the uneven bars gold medal on the Nth tiebreaker; but top-level sporting events whose rules do not admit ties must sometimes decide contests by tiny margins.

A more interesting discussion relates to a change in the scoring system, moving from the old 0.0 to 10.0 scale, to a new scale that adds together an “A score” measuring the difficulty of the athlete’s moves and a “B score” measuring how well the moves were performed. The B score is on the old 0-10 scale, but the A score is on an open-ended scale with fixed scores for each constituent move and bonuses for continuously connecting a series of moves.

One consequence of the new system is that there is no predetermined maximum score. The old system had a maximum score, the legendary “perfect 10”, whose demise is mourned old-school gymnastics gurus like Bela Karolyi. But of course the perfect 10 wasn’t really perfect, at least not in the sense that a 10.0 performance was unsurpassable. No matter how flawless a gymnast’s performance, it is always possible, at least in principle, to do better, by performing just as flawlessly while adding one more flip or twist to one of the moves. The perfect 10 was in some sense a myth.

What killed the perfect 10, as Jordan Ellenberg explained in Slate, was a steady improvement in gymnastic performance that led to a kind of grade inflation in which the system lost its ability to reward innovators for doing the latest, greatest moves. If a very difficult routine, performed flawlessly, rates 10.0, how can you reward an astonishingly difficult routine, performed just as flawlessly? You have to change the scale somehow. The gymnastics authorities decided to remove the fixed 10.0 limit by creating an open-ended difficulty scale.

There’s an interesting analogy to the “grade inflation” debate in universities. Students’ grades and GPAs have increased slowly over time, and though this is not universally accepted, there is plausible evidence that today’s students are doing better work than past students did. (At the very least, today’s student bodies at top universities are drawn from a much larger pool of applicants than before.) If you want a 3.8 GPA to denote the same absolute level of performance that it denoted in the past, and if you also want to reward the unprecendented performance of today’s very best students, then you have to expand the scale at the top somehow.

But maybe the analogy from gymnastics scores to grades is imperfect. The only purpose of gymnastics scores is to compare athletes, to choose a winner. Grades have other purposes, such as motivating students to pay attention in class, or rewarding students for working hard. Not all of these purposes require consistency in grading over time, or even consistency within a single class. Which grading policy is best depends on which goals we have in mind.

One thing is clear: any discussion of gymnastics scoring or university grading will inevitably be colored by nostalgic attachment to the artists or students of the past.

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iPhone Apps Show Industry the Benefits of Openness

August 4, 2008 by

Today’s New York Times reports on the impact of Apple’s decision to allow third-party application software on the iPhone:

In the first 10 days after Apple opened its App Store for the iPhone, consumers downloaded more than 25 million applications, ranging from games like Super Monkey Ball to tools like New York City subway maps. It was nothing short of revolutionary, not only because the number was so high but also because iPhone users could do it at all.

Consumers have long been frustrated with how much control carriers — AT&T, Verizon Wireless, Sprint and the like — have exerted over what they could download to their mobile phones. But in the last nine months, carriers, software developers and cellphone makers have embraced a new attitude of openness toward consumers.

The App Store makes a big difference to me as a new iPhone user – the device would be much less useful without third-party applications. The value of third-party applications and the platforms that enable them is a commonplace outside the mobile phone world. It’s good to see it finally seeping into what Walt Mossberg famously calls “the Soviet Ministries”.

But before we declare victory in the fight for open mobile devices, let’s remember how far the iPhone still has to go. Although a broad range of applications is available in the App Store, the Store is still under Apple’s control and no app can appear there without Apple’s blessing. Apple has been fairly permissive so far, but that could change, and in any case there will inevitably be conflicts between what users and developers want and what Apple wants.

One of Apple’s reasons for opening the App Store must have been the popularity of unauthorized (by Apple) iPhone apps, and the phenomenon of iPhone jailbreaking to enable those apps. Apple’s previous attempt to limit iPhone apps just didn’t work. Faced with the possibility that jailbreaking would become the norm, Apple had little choice but to offer an authorized distribution path for third-party apps.

It’s interesting to note that this consumer push for openness came on the iPhone, which was already the most open of the market-leading mobile phones because it had an up-to-date Web browser. You might have expected less open phones to be jailbroken first, as their users had the most to gain from new applications.

Why was the iPhone the focus of openness efforts? For several reasons, I think. First, iPhone users were already more attuned to the advantages of good application software on mobile phones – that’s one of the reasons they bought iPhones in the first place. Second, Apple’s reputation for focusing on improving customer experience led people to expect more and better applications as the product matured. Third, the iPhone came with an all-you-can-eat Internet access plan, so users didn’t have to worry that new apps would run up their bandwidth bill. And finally, the fact that the iPhone was nearer to being open, having a more sophisticated operating system and browser, made it easier to jallbreak.

This last is an important point, and it argues against claims by people like Jonathan Zittrain that almost-open “appliances” will take the place of today’s open computers. Generally, the closer a system is to being open, the more practical autonomy end users will have to control it, and the more easily unauthorized third-party apps can be built for it. An almost-open system must necessarily be built by starting with an open technical infrastructure and then trying to lock it down; but given the limits of real-world lockdown technologies, this means that customers will be able to jailbreak the system.

In short, nature abhors a functionality vacuum. Design your system to remove functionality, and users will find a way to restore that functionality. Like Apple, appliance vendors are better off leading this parade than trying to stop it.

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